Naming+Molecules

Binary molecular compounds are those that contain only two different elements. In naming such compounds, given their formulas, the rules below are followed:
 * 1) Name the first element in the formula first, using its element name, unchanged.
 * 2) Name the second element, using the root of its name and adding the suffix -ide.
 * 3) Use the following prefixes, given the number of each type of atom present: 1, mono-; 2, di-; 3, tri-; 4, tetra-; 5, penta-; 6, hexa-; 7, hepta-; 8, octa-; 9 nona-; and 10, deca-. Mono- is not used as a prefix for the name of the first element

Example: Naming Binary Molecular Compounds Name the binary molecular compound that has the formula S2O7.

The first element is named first, using the unchanged element name: sulfur. The second element's root is then written with the suffix -ide: ox- plus - ide = oxide. There are two sulfur atoms, so the prefix di- is added. There are seven oxygen atoms, so the prefix hepta- is addes. Thus, the complete name is disulfur heptoxide. (The a in hepta- is dropped before the vowel o in oxide).

A binary acid contains hydrogen and one other element. To name such an acid, use the prefix hydro- to name the hydrogen part of the molecule. Then to a form of the root of the second element name, add the suffix -ic. Finally, add the word acid.
 * Naming Acids**

An oxyanion is a polyatomic ion that contains oxygen. An oxyacid is an acid that contains hydrogen and an ocyanion. To name such an acid, first write a form of the root of the name of the oxyanion. If the oxyanion name ends in -ate, name te acid by adding the suffix -ic to the root. If the oxyanion name ends in -ite, name the acid by adding the suffix -ous to the root. Then add the word acid.

Examples: Naming Acids a. H2Se b. HBrO3

a. H2Se is a binary acid, so the prefix hydro- is used, followed b the root of the name of the second element (selenium, root selen-), followed by the suffix -ic and the word acid. Thus, the name is hydroselenic acid. b. The oxyanion BrO3 is the bromate ion. Its root is brom-. Because the oxyanion name ends in -ate, add the suffix -ic. Then add the word acid. Thus the name is bromic acid.

Given the name of a molecular compound, you can write its formula by analyzing the name in terms of the rules given above. Use the prefixes that indicate the number (mono-, di-, and so on) to write the proper subscripts
 * Writing Formulas from Names**